AQA GCSE Biology Unit 3

Hope you find this useful.

HideShow resource information
Preview of AQA GCSE Biology Unit 3

First 180 words of the document:

AQA GCSE Biology Unit 3
ACTIVE TRANSPORT is the movement of a substance against a concentration gradient. This uses
up energy from respiration (found in the intestines and the kidneys) for absorption and
re-absorption.
Two main ways in which substances move in and out of cells:
DIFFUSION is the net movement of particles moving from an area of high concentration to an
area of low concentration (you could call this the OSMOSIS for substances)
OSMOSIS- the diffusion of water across a partially permeable membrane
BOTH DIFFUSION AND OSMOSIS GO ALONG A CONCENTRATION GRADIENT
UNLIKE ACTIVE TRANSPORT WHICH GOES AGAINST THE CONCENTRATION GRADIENT
Energy for active transport comes from the energy created when cells respire- also know as
"cellular respiration". If a cell respires a lot and creates a lot of energy, it can carry out lots
of active transport. Examples of these cells include root hair cells and gut lining cells.
If cells have lots of mitochondria they also provide a lot of energy:

Other pages in this set

Page 2

Preview of page 2

Here's a taster:

The Breathing System
Breathe out- Ribcage down and out, Diaphragm up (domed shape) forcing carbon dioxide out of
the lungs
Breathe in- Ribcage up and out, Diaphragm down (flattened)
AIR MOVES INTO THE MOUTH, DOWN THE TRACHEA, DOWN A BRONCHI, DOWN INTO THE
BRONCHIOLES AND INTO THE ALVEOLI
The part that separates the lungs from the abdomen (lower part of the body) is a strong sheet of
muscle called the diaphragm.…read more

Page 3

Preview of page 3

Here's a taster:

Our breathing system takes air IN and OUT of the body, and helps the body to salvage
oxygen required for respiration and to get rid of waste carbon dioxide produced when cells
respire.
Alveoli provide a large, moist surface area with a rich blood supply and have thin walls to
make diffusion as efficient as possible.…read more

Page 4

Preview of page 4

Here's a taster:

The Circulatory System
Oxygenated blood is pumped to the heart from the lungs, and from the body to the heart
De- oxygenated blood is pumped from the heart to the lungs and from the body back to the
heart
ARTERIES: CARRY BLOOD AWAY FROM THE HEART
VEINS: CARRY BLOOD TO THE HEART
CAPILLARIES: TINY BLOOD VESSELS FOUND NEAR ORGANS AND TISSUES OF THE BODY THAT
EXCHANGE SUBSTANCES WITH THE CELLS (E.G.…read more

Page 5

Preview of page 5

Here's a taster:

BLOOD...
WHITE BLOOD CELLS: HELP TO FIGHT INFECTION
There are two different types of white blood cells;
Phagocytes: engulf and ingest the foreign body/ bacteria
Lymphocytes: create unique antibodies that are designed to specifically target the bacteria/disease
etc the body is being faced with. The antibodies created latch on to the subject and then destroy it.…read more

Page 6

Preview of page 6

Here's a taster:

HAEMOGLOBIN: RELEASES OXYGEN INTO CELLS substance which gains oxygen from the lungs
to form OXYHAEMOGLOBIN
Exchange of materials in plants
Plants need to exchange like humans and animals do, and they too also use the three methods of
exchanging materials; DIFFUSION, OSMOSIS & ACTIVE TRANSPORT
DIFFUSION: to get carbon dioxide needed for photosynthesis
OSMOSIS: to take up water from the soil
ACTIVE TRANSPORT: to obtain minerals from the soil
Plants are designed to help these three processes take place efficiently, for
example:
- The flattened…read more

Page 7

Preview of page 7

Here's a taster:

THEREFORE leaves
are well adapted to CONTROL INPUT & OUTPUT of carbon dioxide.
THE STOMATA
Plants have small openings on the underside of their leaves that can
be opened when the plant needs carbon dioxide; however the stomata
stay closed when the plant does not need carbon dioxide to prevent water loss. Carbon dioxide
enters the stomata via DIFFUSION. Stomata are opened and closed by GUARD CELLS.
Transpiration
When a plant leaves the stomata open to let in carbon dioxide, water is still lost.…read more

Page 8

Preview of page 8

Here's a taster:

WILTING; wilting occurs when the plant looses water faster than it is gaining from the roots. The
plant hangs down which greatly reduces the surface area for water loss.
The Kidneys
Protein is vital for growth and repair, however sometimes we eat more protein than our body
needs. Excess Protein creates amino acids, which are then broken down into smaller molecules in
the liver forming ammonia. Ammonia is very poisonous so it is then converted into the less
poisonous urea.…read more

Page 9

Preview of page 9

Here's a taster:

Kidney Problems & Dialysis
Kidneys can fail because of an infection, a bad case of poisoning, injury with severe loss of blood
or very high blood pressure. Fortunately kidney failure is uncommon. It is possible to live with
only one kidney however if both kidneys fail options open are a treatment called dialysis or a new
kidney (kidney transplant). Kidney failure is when the kidney can no longer filter the blood
efficiently, therefore poisoning the body.…read more

Page 10

Preview of page 10

Here's a taster:

If the patient has a dialysis machine, it can be carried out at home
Longer living life
Cons
Inconvenience- hospital visits have to take place 3 times a week
Time consuming- dialysis must be carried out for 3-4 hours 3 times a week
Expensive
Kidney transplant- Advantages and Disadvantages
Pros
If the kidney is accepted by the patient's body, they have a strong chance of living a
normal life free from dialysis
Cons
Kidneys can be rejected by the patients body
Kidneys suitable for transplant…read more

Comments

No comments have yet been made

Similar Biology resources:

See all Biology resources »See all resources »